LSI for specific purposes (Application Specific Integrated Circuits: ASIC) are provided with a plurality of logic cells that serve as basic logic circuits, the logic cells that are to be put into operation being selected to match a user's specifications. ASIC include conventional ASIC in which the logic cells are determined in an interconnect patterning step in the fabrication process and programmable logic (reconfigurable logic integrated circuits) in which the logic cells are determined by the user after shipment of the product. Although conventional ASIC has the merit of cheap product unit cost realized by mass production, it suffers from the demerits of high development cost and lengthy development time. On the other hand, although programmable logic has higher product unit price, slower operating speed, and increased power consumption than conventional ASIC, it enjoys the advantages of lower development cost and shorter development time. Development is currently underway to both improve the operational performance and reduce the size of switching elements for programming for the purposes of achieving programmable logic having lower product unit cost, faster operating speed, and lower power consumption.
The application of the programmable device disclosed in JP-A-2002-536840 (hereinbelow referred to as Patent Document 1) for the switching elements of programmable logic can be considered. The following simplified explanation regards the configuration for a case in which the two-terminal switch of this programmable device is applied to a switching element.
The programmable device disclosed in Patent Document 1 is made up from a multiplicity of logic cells arranged in the form of a two-dimensional array, interconnects for interconnecting logic cells, and a multiplicity of two-terminal switches for switching between connection and non-connection between interconnects. Switching the connection states (connection/non-connection) of the two-terminal switches sets the configuration of the interconnects between logic cells and the functions of the logic cells and thus can realize a logic integrated circuit that matches certain specifications.